Harvey Two-Face Dent is a fictional supervillain appearing in American comic books published by DC Comics, commonly as an adversary of the superhero Batman. The character was created by Bob Kane and Bill Finger, and first appeared in Detective Comics #66 (Aug. 1942).
reactivity. 1  the quality or condition of being reactive. 2  Chemistry. the relative capacity of an atom, molecule, or radical to undergo a chemical reaction with another atom, molecule, or compound. 3  Physics. a measure of the deviation from the condition at which a nuclear reactor is critical.
reaction. 1. opposite action or counteraction; the response of a part to stimulation. 2. the phenomena caused by the action of chemical agents; a chemical process in which one substance is transformed into another substance or substances. chain reaction. one which is self-propagating; a chemical process in which each time a free radical is destroyed a new one is formed.